Engines, such as, internal combustion engines, including diesel engines, gasoline engines, gaseous fuel-powered engines, for example, exhaust a complex mixture including different types of constituent components, including gaseous compounds, such as nitrogen oxides (NOx), and solid particulate matter, also known as soot. Exhaust emission standards have become increasingly more stringent, and the amount of NOx and soot emitted to the atmosphere by an engine can be regulated depending on the type of engine, size of engine, and/or class of engine.
In order to ensure compliance with the regulation of NOx, some engine manufacturers have implemented a strategy called selective catalytic reduction (SCR). SCR is a process where a gaseous or liquid reductant, most commonly urea, is injected into the exhaust stream of an engine and is absorbed onto a substrate. The reductant reacts with NO in the exhaust gas to form water (H2O) and nitrogen (N2). Although SCR can be effective, it is most effective when the reductant is maintained below certain threshold temperatures.
SCR systems often include an injector for spraying the reductant. Under unfavorable conditions, the exhaust gas temperatures at the region where the injector introduces the reductant into the exhaust can reach more than 500° C. This high temperature may adversely impact the efficacy of the reductant injected into the exhaust stream and can harm the injector itself.
U.S. Pat. No. 6,513,323 is entitled, “Valve Seat Device For a Metering Valve of an Exhaust Treatment Station.” The '323 patent is directed to an uncontrolled heat pipe used in a valve seat device for transferring the waste heat from the exhaust gas acting on a metering valve to a condensation zone which is situated in a lower temperature environment, whereby the metering valve is cooled sufficiently to prevent a chemical change of a reducing agent which otherwise can be caused by high temperatures.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some aspects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.